DD is 6 and in year 2. She was reading before she started school and now has a reading age of 10.10 and a comprehension age of 10.7. She reads various books independently and has brought home all sorts of books from school - animal ark, secret seven, etc. She loves them, loves reading and understands what she reads.
The school have just bought in lots of new independent reading books - lots of the higher Oxford reading tree treetops levels, etc. She's had a few of these and enjoyed them. She reads them and then answers the comprehension questions.
We've had a note home today in her reading record asking us to make sure she reads every book twice and answers the comprehension questions. I can understand getting children who are still sounding out and developing fluency to read books twice. But a fluent, confident reader who understands what she is reading? What is the point of getting her to read a book twice? She will do it if I tell her to as she is compliant, but she wasn't impressed when I told her! 
Any ideas?